DESCRIPTION: (provided by the applicant): Our working hypothesis is that proteins relating to tick feeding can be manipulated to inhibit tick feeding and interrupt pathogen transmission. To test this hypothesis, methods must be developed to produce large amounts of purified, highly active proteins to immunize hosts and assess the effects on tick feeding, host response and pathogen transmission in vivo We have isolated, cloned and purified the tick cytokine- macrophage migration inhibitory factor (MIF. Jaworski et al. 2001), we have demonstrated that MIF is highly active by inhibiting random macrophage migration by more than 58 percent and can be purified to homogeneity. What remains is to demonstrate that MIF can elicit (induce) local effects at the tick feeding site, We propose that tick MIF has a role m tick feeding that can be measured during tick feeding. Specifically, we hypothesize that tick MIF entering the feeding lesion in the earliest days of adult feeding increases inflammation at the feeding site, Our specific aims are: 1) To determine the presence and abundance of MIF protein in tick saliva, salivary glands, midgut epithelium and hemolymph during adult tick feeding; and to determine if MIF gene expression parallels the protein profiles using Northern analyses and RT-PCR of mRNA isolated from the midgut and salivary glands: 2) To compare the effects of MIF with tick saliva on macrophage migration using Random Macrophage Migration (RMM) assays and to test whether anti-MIF antibodies can neutralize MIF and tick saliva in vitro, To determine the effects of host cytokines that are important to tick feeding like IL-2. IL-4. IL-10 and IFN-gamma on RMM when used in combination with MIF and tick saliva; and, 3) To determine MIF function in tick feeding. To immunize rabbits and rats with purified MIF or anti-MIF antibodies (passive immunization) and follow tick feeding events through laser dopIer measurements, cytochemistry of tick and feeding lesion tissues, photographic documentation as well as measurements of feeding periods, engorgement weights and fecundity. Through the proposed study we expect to gain insight into the immunoregulatory role of MIF in tick feeding and pathogen transmission.